Though JPMorgan Chase CEO Jamie Dimon characterized his throat cancer as "curable," it's "not exploitative" to think about his successor, Jeffrey Sonnenfeld, a professor at the Yale School of Management, told CNBC on Wednesday.

In a note to staff, Dimon said his cancer is believed to be contained in his throat and lymph nodes on his right side. The 58-year-old plans to remain actively involved in the largest U.S. bank's business, even as he undergoes radiation and chemotherapy treatment that is expected to last about eight weeks.

To Sonnenfeld, Dimon has done a good job of raising the profile of these executives. But in any case, Dimon will be a "tough act to follow."

"He is absolutely iconic. He is probably the most feared and revered man in finance today. ... He has proven himself many times over," Sonnenfeld said. "He's a comeback superstar in his personal career and also in the, what, 48 percent return in stock price in this company and despite the crazy pounding of some of those penalties they had to withstand. Still, they turned out record profits."